DESCRIPTION (Applicant?s Abstract): The abuse of methamphetamine is rising rapidly in the United States (National Institute on Drug Abuse, 1999) and the drug has been identified as a target for increased investigation by the National Institute on Drug Abuse (NIDA) (Mathias, 1998). Because of the potentially serious implications of chronic methamphetamine use for both the adult abuser and infants exposed prenatally, it is imperative that animal models be developed in which the parameters of methamphetamine abuse and its prevention and treatment can be explored. Determining the interactions between experiential and drug stimuli as they affect the behavior of other species is a critical link in understanding similar processes in humans. In this series of proposed studies, the behavior of methamphetamine-exposed Long-Evans hooded rats reared in an enriched, complex environment will be compared to that of rats reared in a restricted, standard laboratory environment as well as to non-exposed control animals. Also, rats that have been prenatally exposed to methamphetamine will be simi1arly assessed to determine whether sensitivity to environmental enrichment can exert "retroactive" effects as well by modifying the effects of drugs administered during the prenatal period. Drug effects will be tested across a variety of tasks (open field activity patterns, acoustic startle, Hampton Court maze). Each task taps into a different aspect of behavior (affect, activity, and complex cognition) that has been linked with methamphetamine-associated deficits. Taken together, the data from all of the studies should provide a portrait of the nature of the behavioral disruptions induced by methamphetamine, the effects of differential early rearing, and the interaction between these two factors. Particular relevance of this study exists for the application of early intervention strategies to children and adults who have been exposed to drugs of abuse, in that this series of studies win help delineate the range of behaviors affected by rearing environment and drug administration, and will determine the impact of enrichment on prenatal drug exposure versus that experienced after birth.